1. Field of the Invention
This invention relates to a burner assembly having an accessible ignitor on a torch tip wherein an ignitor actuated by a push button is mounted on a back piece to circumscribe a mixing chamber for air and gas such as acetylene, Mapp, propane, or the like; and more particularly, to such an tip wherein an actuator button for a piezoelectric ignitor is orientated for actuation by applying a force in the direction opposite to a torch handle or torch regulator assembly to which the ignitor tip is detachably connected.
2. Description of the Prior Art
It is well known practice to ignite a gas-air mixture formed by a hand-held burner through the use of a spark generating device. An operator first establishes a flow of a combustible air gas mixture emerging from a torch tip and then by holding a spark generating device close to the tip, the occurrence of a spark ignites the combustible air gas mixture. An example of such a burner can be found in my U.S. Pat. No. 4,886,447. Recent developments in this general type of burner provide for the integration of an electrically powered ignitor, e.g., piezoelectric apparatus, with the burner thereby avoiding the need to maintain the separate mechanical spark or flame source.
Examples of a burner assembly having an ignitor combined therewith can be found in the following patents: U.S. Pat. No. 4,348,172; U.S. Pat. No. 4,526,532; U.S. Pat. No. 4,804,324; U.S. Pat. No. 4,720,259; U.S. Pat. No. 4,881,894; U.S. Pat. No. 4,952,138; U.S. Pat. No. 4,954,078; U.S. Pat. No. 5,071,342; and U.S. Pat. No. 5,123,837. From this body of prior art there can be found a disclosure of a torch tip assembly wherein a piezoelectric ignitor and actuator button are mounted on a burner tube at any one of diverse places with regard to air inlet openings for a mixing chamber. In U.S. Pat. Nos. 4,348,172 and 4,881,894 there are disclosed high tension wires for a piezoelectric ignitors extending externally along the burner tubes to sites where an opening is provided in the burner tubes for passage of the high tension wire interiorly of the tubes an thence along the interior of the tubes to selected site where spark gap is formed with the burner tubes. In such an arrangement, the opportunity exists for an unwanted leakage of combustible gas from the openings where the high tension wires pass through the walls of the burner tube. Not only does the opportunity exist for the combustion of the gas leaking from the opening in the burner tube, but also deterioration to insulation due to thermal excursions of the burner tube at the entrance site throughout the operation of the torch.
It is undesirable to expose ignition lead wire to the environment that might allow damage to the lead wire or disconnection from the anchor site. In this regard, when an ignition lead wire enters a burner tube at a site downstream from the ignitor housing, it is prone to failure the attempts to maintain the gas type seal which can be damaged when used or bumped or when stored. Also, the combustible gas stream is completely combustible at a site downstream of a mixing chamber when chosen as an entry site in the burner tube for the lead wire. The lead wire and any attempts to provide a protective enclosure obstructs the operators view of the work area during use of the torch tip. It can also be found from this prior art that a housing with complex construction is utilized for separating and mounting a gas control valve as well as an ignitor onto the basic structure of the gas appliance. The complexity of the housing construction discourages and usually inhibits necessary occurring replacement of the piezoelectric ignitor when it fails service.
When a gas control valve and piezoelectric ignitor are integrated in a burner assembly, should the burner tube of the assembly, for example, be damaged, then the entire assembly including ignitor and gas control valve must be discarded. The burner tube is pone to wear and tear because of the thin wall tube design which also make it subject to damage when dropped or impacted. In the known design, when the ignitor is supported in an housing by a burner tube, the ignitor is too remote to the handle or other hand gripping surface to enable support of the torch by the same hand used to operate the ignitor. Moreover, the stress and stain imparted on the burner tube by the operation of the piezoelectric ignitor requires special measures to protect the burner tube against fatigue. A problem still remains in regard to the degregation of the close tolerance fit and "O" ring used in the quick release connection between the handle and the torch tip assembly. The need exists, therefore, to provide an ignitor housing to fit the back piece of a replaceable ignitor tip and provide a passageway for a high tension wire to the interior of the burner tube in such a manner so as to avoid the possibility of leakage of a combustible gas mixture to the atmosphere.
Accordingly, it is an object of the invention to provide in a burner assembly an ignitor housing affixed to a back piece of a torch tip which is detachable from a torch handle or a torch regulator and always remains impervious to heating throughout operation of the burner assembly to avoid thermal damage to the ignitor housing.
It is a further object of the present invention to provide an ignitor arranged in a torch tip in a manner to allow operation of the ignitor push button by the thumb or finger of the persons hand which also grips and supports the torch handle or regulator.
It is a further object of the present invention to provide a housing which is mounted on the back piece of a torch tip in a manner that will allow dimensioning of the ignitor to fit a multiplicity of differently sized torch tips while protecting the ignitor lead wire through utilization of air inlet openings of a mixing chamber in the back piece for passage in the lead wire to the interior of the burner tube.